No co operation in regard to solving my problem

I signed for vehicle finance with a fixed interest rate. After a year , my interest rate went up. I called their vehicle finance department from inside the bank , as there is no alternative number for custormers to call. The lady who helped me , said that I must email my contract and proof that I signed for a fixed interest rate. I did so. After hearing nothing from her after three days , I emailed her again , asking her kindly please just to let me know of any developments. I haven't heared from her since. How does this happen that I sign for a fixed interest rate , but then I get a linked interest rate?? No , Its bad service indeed.